Serrasalminae
Encyclopedia
Serrasalminae is a subfamily of fish within the family Characidae
. The name means "serrated salmon
family", which refers to the serrated
keel running along the belly of these fish.
These common names generally designate differing dental characteristics
and feeding habits.
or scute
s, and a long dorsal fin
(over 16 rays). Most species also possess an anteriorly-directed spine just before the dorsal fin extending from a supraneural bone; exceptions include members of the genera Colossoma, Piaractus, and Mylossoma.
Most serrasalmines have about 60 chromosome
s, ranging from 54 to 62.Metynnis has 62 chromosomes, as does Catoprion, Pristobrycon striolatus, and Pygopristis.
river systems in South America
, but have been introduced to other areas. Species range from about 10° N latitude
south to about 35° S latitude.
s, fruit
s, leaves
, various invertebrate
and vertebrate
prey, as well as fish flesh, scales, and fins. To emphasize the diversity of diets, authors commonly highlight the fruit- and leaf-eating pacus and the highly carnivorous piranhas. Most non-piranhas in the family are primarily herbivorous. In contrast, it was long believed that piranhas were strict carnivore
s. Many species change diets depending on age and resource availability.
. However, some sources classify these fish in their own family, Serrasalmidae. The relationship of Serrasalminae to other characiforms has yet to be determined. The taxonomy
and systematics of piranhas and their relatives are complicated and much remains unsettled. Consequently, both species identification and phylogenetic
placement of many taxa are problematic.
However, the ongoing classification of these fish is difficult and often contentious, with ichthyologists
basing ranks according to characteristics that may overlap irregularly (see Cladistics
). DNA
research sometimes confounds rather than clarifies species ranking. Ultimately, classifications can be rather arbitrary.
Despite this, Serrasalminae is relatively well understood, and there is wide agreement on the genera and species that it includes.
, although a few unidentified forms are considered Paleocene
and two reportedly date to as early as the Late Cretaceous
. Fossils of a living species of Colossoma from the Miocene have been described, suggesting a very conservative history for a specialized herbivorous fish. All serrasalmine genera had originated by the middle Miocene, with the possible exception of three of the four piranha genera (Pygocentrus, Pristobrycon, and Serrasalmus).
ornamentals, and several pacus, such as Piaractus and Colossoma, are economically important
to commercial fisheries
and aquaculture
.
Piranhas are generally less valued, although they are commonly consumed by subsistence fishers and frequently sold for food in local markets. A few piranha species occasionally appear in the aquarium trade, and, in recent decades, dried specimens have been marketed as tourist souvenir
s. Piranhas occasionally bite and sometimes injure bathers and swimmers, but serious attacks are rare and the threat to humans has been exaggerated. However, piranhas are a considerable nuisance to commercial and sport fishers because they steal bait, mutilate catch, damage nets and other gear, and may bite when handled.
Characidae
The Characidae, characids or characins are a family of freshwater subtropical and tropical fish, belonging to the order Characiformes. The name "characins" is the historical one, but scientists today tend to prefer "characids" to reflect their status as a by and large monophyletic group at family...
. The name means "serrated salmon
Salmon
Salmon is the common name for several species of fish in the family Salmonidae. Several other fish in the same family are called trout; the difference is often said to be that salmon migrate and trout are resident, but this distinction does not strictly hold true...
family", which refers to the serrated
Serration
Serration generally refers to a saw-like appearance or a row of sharp or tooth-like projections. A serrated cutting edge has many small points of contact with the material being cut. By having less contact area than a smooth blade or other edge, the applied force at each point of contact is...
keel running along the belly of these fish.
Common names
Fish classified as Serrasalminae are also known by the following common names:- PacuPacúPacu or pacú is the common name of several South American fishes.PACU, Pacu or pacú may also refer to:*Piaractus mesopotamicus , a South American ray-finned fish that is endemic to the Paraguay-Paraná River basin*Tambaqui , known as black pacu, black-finned pacu, giant pacu*Philippine Association...
- PiranhaPiranhaA piranha or piraña is a member of family Characidae in order Characiformes, an omnivorous freshwater fish that inhabits South American rivers. In Venezuela, they are called caribes...
- Silver dollar
These common names generally designate differing dental characteristics
Dentition
Dentition pertains to the development of teeth and their arrangement in the mouth. In particular, the characteristic arrangement, kind, and number of teeth in a given species at a given age...
and feeding habits.
Description
Serrasalmines are medium to large-sized characids that reach about 1 metres (3.3 ft)long, generally characterized by a deep, laterally compressed body with a series of mid-ventral abdominal spinesSpine (zoology)
A spine is a hard, thorny or needle-like structure which occurs on various animals. Animals such as porcupines and sea urchins grow spines as a self-defense mechanism. Spines are often formed of keratin...
or scute
Scute
A scute or scutum is a bony external plate or scale, as on the shell of a turtle, the skin of crocodilians, the feet of some birds or the anterior portion of the mesonotum in insects.-Properties:...
s, and a long dorsal fin
Dorsal fin
A dorsal fin is a fin located on the backs of various unrelated marine and freshwater vertebrates, including most fishes, marine mammals , and the ichthyosaurs...
(over 16 rays). Most species also possess an anteriorly-directed spine just before the dorsal fin extending from a supraneural bone; exceptions include members of the genera Colossoma, Piaractus, and Mylossoma.
Most serrasalmines have about 60 chromosome
Chromosome
A chromosome is an organized structure of DNA and protein found in cells. It is a single piece of coiled DNA containing many genes, regulatory elements and other nucleotide sequences. Chromosomes also contain DNA-bound proteins, which serve to package the DNA and control its functions.Chromosomes...
s, ranging from 54 to 62.Metynnis has 62 chromosomes, as does Catoprion, Pristobrycon striolatus, and Pygopristis.
Distribution
Serrasalmines inhabit all major and some minor Atlantic riverRiver
A river is a natural watercourse, usually freshwater, flowing towards an ocean, a lake, a sea, or another river. In a few cases, a river simply flows into the ground or dries up completely before reaching another body of water. Small rivers may also be called by several other names, including...
river systems in South America
South America
South America is a continent situated in the Western Hemisphere, mostly in the Southern Hemisphere, with a relatively small portion in the Northern Hemisphere. The continent is also considered a subcontinent of the Americas. It is bordered on the west by the Pacific Ocean and on the north and east...
, but have been introduced to other areas. Species range from about 10° N latitude
Latitude
In geography, the latitude of a location on the Earth is the angular distance of that location south or north of the Equator. The latitude is an angle, and is usually measured in degrees . The equator has a latitude of 0°, the North pole has a latitude of 90° north , and the South pole has a...
south to about 35° S latitude.
Ecology
The diets of the various serrasalmid fishes include seedSeed
A seed is a small embryonic plant enclosed in a covering called the seed coat, usually with some stored food. It is the product of the ripened ovule of gymnosperm and angiosperm plants which occurs after fertilization and some growth within the mother plant...
s, fruit
Fruit
In broad terms, a fruit is a structure of a plant that contains its seeds.The term has different meanings dependent on context. In non-technical usage, such as food preparation, fruit normally means the fleshy seed-associated structures of certain plants that are sweet and edible in the raw state,...
s, leaves
Leaves
-History:Vocalist Arnar Gudjonsson was formerly the guitarist with Mower, and he was joined by Hallur Hallsson , Arnar Ólafsson , Bjarni Grímsson , and Andri Ásgrímsson . Late in 2001 they played with Emiliana Torrini and drew early praise from the New York Times...
, various invertebrate
Invertebrate
An invertebrate is an animal without a backbone. The group includes 97% of all animal species – all animals except those in the chordate subphylum Vertebrata .Invertebrates form a paraphyletic group...
and vertebrate
Vertebrate
Vertebrates are animals that are members of the subphylum Vertebrata . Vertebrates are the largest group of chordates, with currently about 58,000 species described. Vertebrates include the jawless fishes, bony fishes, sharks and rays, amphibians, reptiles, mammals, and birds...
prey, as well as fish flesh, scales, and fins. To emphasize the diversity of diets, authors commonly highlight the fruit- and leaf-eating pacus and the highly carnivorous piranhas. Most non-piranhas in the family are primarily herbivorous. In contrast, it was long believed that piranhas were strict carnivore
Carnivore
A carnivore meaning 'meat eater' is an organism that derives its energy and nutrient requirements from a diet consisting mainly or exclusively of animal tissue, whether through predation or scavenging...
s. Many species change diets depending on age and resource availability.
Taxonomy
Currently, Serrasalminae are classified as a subfamily of CharacidaeCharacidae
The Characidae, characids or characins are a family of freshwater subtropical and tropical fish, belonging to the order Characiformes. The name "characins" is the historical one, but scientists today tend to prefer "characids" to reflect their status as a by and large monophyletic group at family...
. However, some sources classify these fish in their own family, Serrasalmidae. The relationship of Serrasalminae to other characiforms has yet to be determined. The taxonomy
Taxonomy
Taxonomy is the science of identifying and naming species, and arranging them into a classification. The field of taxonomy, sometimes referred to as "biological taxonomy", revolves around the description and use of taxonomic units, known as taxa...
and systematics of piranhas and their relatives are complicated and much remains unsettled. Consequently, both species identification and phylogenetic
Phylogenetics
In biology, phylogenetics is the study of evolutionary relatedness among groups of organisms , which is discovered through molecular sequencing data and morphological data matrices...
placement of many taxa are problematic.
However, the ongoing classification of these fish is difficult and often contentious, with ichthyologists
Ichthyology
Ichthyology is the branch of zoology devoted to the study of fish. This includes skeletal fish , cartilaginous fish , and jawless fish...
basing ranks according to characteristics that may overlap irregularly (see Cladistics
Cladistics
Cladistics is a method of classifying species of organisms into groups called clades, which consist of an ancestor organism and all its descendants . For example, birds, dinosaurs, crocodiles, and all descendants of their most recent common ancestor form a clade...
). DNA
DNA
Deoxyribonucleic acid is a nucleic acid that contains the genetic instructions used in the development and functioning of all known living organisms . The DNA segments that carry this genetic information are called genes, but other DNA sequences have structural purposes, or are involved in...
research sometimes confounds rather than clarifies species ranking. Ultimately, classifications can be rather arbitrary.
Despite this, Serrasalminae is relatively well understood, and there is wide agreement on the genera and species that it includes.
Fossil record
The fossil record, particularly for piranhas, is relatively sparse. Most known fossils are from the MioceneMiocene
The Miocene is a geological epoch of the Neogene Period and extends from about . The Miocene was named by Sir Charles Lyell. Its name comes from the Greek words and and means "less recent" because it has 18% fewer modern sea invertebrates than the Pliocene. The Miocene follows the Oligocene...
, although a few unidentified forms are considered Paleocene
Paleocene
The Paleocene or Palaeocene, the "early recent", is a geologic epoch that lasted from about . It is the first epoch of the Palaeogene Period in the modern Cenozoic Era...
and two reportedly date to as early as the Late Cretaceous
Cretaceous
The Cretaceous , derived from the Latin "creta" , usually abbreviated K for its German translation Kreide , is a geologic period and system from circa to million years ago. In the geologic timescale, the Cretaceous follows the Jurassic period and is followed by the Paleogene period of the...
. Fossils of a living species of Colossoma from the Miocene have been described, suggesting a very conservative history for a specialized herbivorous fish. All serrasalmine genera had originated by the middle Miocene, with the possible exception of three of the four piranha genera (Pygocentrus, Pristobrycon, and Serrasalmus).
Relationship to humans
Many serraslminae are in demand as aquariumAquarium
An aquarium is a vivarium consisting of at least one transparent side in which water-dwelling plants or animals are kept. Fishkeepers use aquaria to keep fish, invertebrates, amphibians, marine mammals, turtles, and aquatic plants...
ornamentals, and several pacus, such as Piaractus and Colossoma, are economically important
to commercial fisheries
Fishery
Generally, a fishery is an entity engaged in raising or harvesting fish which is determined by some authority to be a fishery. According to the FAO, a fishery is typically defined in terms of the "people involved, species or type of fish, area of water or seabed, method of fishing, class of boats,...
and aquaculture
Aquaculture
Aquaculture, also known as aquafarming, is the farming of aquatic organisms such as fish, crustaceans, molluscs and aquatic plants. Aquaculture involves cultivating freshwater and saltwater populations under controlled conditions, and can be contrasted with commercial fishing, which is the...
.
Piranhas are generally less valued, although they are commonly consumed by subsistence fishers and frequently sold for food in local markets. A few piranha species occasionally appear in the aquarium trade, and, in recent decades, dried specimens have been marketed as tourist souvenir
Souvenir
A souvenir , memento, keepsake or token of remembrance is an object a person acquires for the memories the owner associates with it. The term souvenir brings to mind the mass-produced kitsch that is the main commodity of souvenir and gift shops in many tourist traps around the world...
s. Piranhas occasionally bite and sometimes injure bathers and swimmers, but serious attacks are rare and the threat to humans has been exaggerated. However, piranhas are a considerable nuisance to commercial and sport fishers because they steal bait, mutilate catch, damage nets and other gear, and may bite when handled.